Jul 21, 2017 | By Tess

Nathan Seidle, the founder of Colorado-based open source hardware supplier SparkFun, has demonstrated how a 3D printed robot he built and programmed was able to crack a safe in just 15 minutes. The DIY safe-cracking robot only cost about $200 to make.

The project began last Christmas, when Seidle’s wife gifted him with a locked safe she had found on Craigslist. The safe, a $120 SentrySafe, had been sold by its owner because they forgot its initial combination. As a lover of DIY projects and challenges, the safe seemed like the perfect gift for Seidle.

With the same version of the safe at home, Seidle was able to investigate the device’s structure in close detail, which enabled him to come up with a design for a robot specifically built for cracking a SentrySafe. Along with his team at SparkFun, the maker spent roughly four months designing, printing, testing, and tweaking the robot.

The robot itself consists of several 3D printed parts (including the bit that fits around the safe’s dial), an aluminum frame, magnets to secure the bot to the safe, an Arduino board ($20), a motor ($40), and a number of sensors programmed to see if the robot turned the safe’s handle properly.

Over the course of the four months of development, Seidle adapted and refined the safe-cracking robot, which was built to automatically test every combination of the safe. This approach, called “bruteforcing,” was not totally feasible, however, as it would take the robot about four months to test every possible three-number combination (of which there about a million).

To reduce the work for the robot, Seidle figured out a number of vulnerabilities in the safe’s design which could be exploited. First, he realized that the safe has a flight tolerance for error, meaning that a number above or below the proper combination number would work as well. (For instance, if the combination started with a 5, a 4 or 6 would work.) This realization meant that instead of testing every number of the combination, every third number would suffice.

Seidle also discovered that the safe’s dial did not need to be fully returned to its original position after trying a combination, and could carefully turn the dial in a way that kept two of the three rotors in place while the last number was changed. This trick, said Seidle, meant his robot could open the safe in under a day and a half.

Funnily enough, the final trick that enabled the bot to open the lock in as little as 15 minutes actually came from a design feature that was meant to prevent safecrackers from opening the safe: the combination indents. Upon careful inspection, Seidle noticed that the indents of the third rotor (the final number) all measured the same width except one, which was a hundredth of an inch narrower than the other eleven indents.

This led him to realize that if his robot could measure which indent was narrower than the others on the locked safe, the last number of the combination could be found instantly. This feature reduced the robot’s working time down to a maximum of 73 minutes and, as we’ve been saying, a minimum of just 15 minutes.

Ultimately, Seidle is not aiming to become a professional safe-cracker, as he hopes his project will help safe-making companies to realize that vulnerabilities in their products can be exploited relatively easily, with 3D printing and low-cost electronics making safe-cracking tools more accessible than ever.

(Images: SparkFun)

"You’re going to have an army of geeks like myself poking and prodding and trying to do things like this," Seidle told Wired. "The nature of the toolset is getting cheaper, so more nerds are getting brave with their puzzling.”

Seidle will be demonstrating his 3D printed safe-cracking robot at Defcon, the hacker convention held annually in Las Vegas. There, he’s going to be breaking into the $160 SentrySafe model in front of a live audience. The newer safe model also incorporates a key lock, which Seidle found he could break using a ball point pen. “They added a layer of security that is completely useless,” he said.

 

 

Posted in 3D Printing Application

 

 

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Stefan wrote at 7/24/2017 8:48:09 PM:

But.... what was inside the safe when they opened it the first time? :D



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